"Soy Phytoestrogens for Menopause Hot Flashes"
When women hit menopause and their ovaries shut down,
the estrogen level in their body drops 95%.
This is good news for the endometrium, the lining of the uterus.
Otherwise the constant estrogen signaling
could eventually result in endometrial cancer.
In fact, maybe that's why menopause evolved:
to protect the uterus from cancer.
Lower estrogen levels are also good
for lowering breast cancer risk.
In postmenopausal women, relatively high blood levels of estrogen
are associated with a more than double increased risk for breast cancer.
Estrogen levels drop 95% at menopause,
but not to zero, because other tissues
can make estrogen, like our own fat cells.
This probably explains the increase in breast cancer risk
in obese postmenopausal women.
More fatty tissue means more estrogen production.
Now we learned that soy phytoestrogens
can block the production of estrogen,
such that drinking a glass of soymilk with each meal
can cut estrogen levels in half
in premenopausal women.
But levels in postmenopausal women
are already down 95%, and because of that,
many women suffer from hot flashes.
Might lowering levels even further
with soy make menopausal symptoms even worse?
Estrogen treatment is very effective
in reducing menopausal symptoms.
Unfortunately, the downside
is not only the uterine cancer,
but blood clots, strokes,
and cognitive impairment.
Taking progesterone-type compounds
with the estrogen helps prevent
the uterine cancer, but increases
the risk of heart attacks,
more stroke risk, breast cancer,
more clots, and dementia.
So what's a woman to do?
Well, the 80% hot flashes figure is not universal.
Maybe 80 to 85% in European and American women,
but it may be as low as just 15% in places like Japan.
In fact, there's not even a word for it in the Japanese language,
which supports how relatively rare it is.
Maybe the phytoestrogens in soy are helping?
The association between soy product intake
and the occurrence of hot flashes was examined
by following a thousand Japanese women
before they started menopause, over time,
to see who developed hot flashes and who didn't.
And those women who were eating
like 4 ounces of tofu a day
appeared to cut their risk in half,
compared to women who only ate an ounce or two a day,
suggesting soy products are protective.
But maybe soy intake is just
a marker for a healthier diet over all?
A study in China found that the
consumption of whole plant foods
in general seemed to be associated
with decreased menopausal symptoms.
So to see if soy was something special,
you'd have to put it to the test.
Studies like this, of soy phytoestrogens in pill form,
showed extraordinary results,
a significant drop in hot flash presence,
number, and severity—from 100%
of women suffering at the beginning
to only 31% suffering by the end of 3 months.
The average number of hot flashes dropped
from about 120 a month down to 12.
But the problem with studies like these
is that there's no control group
to control for the placebo effect.
If you look at all the hormone trials,
even the women who got the placebo sugar pills
had up to a 60% reduction in hot flashes over the years.
That's why any therapy purported to reduce such symptoms
must be assessed in blinded trials against a placebo
because of the large placebo effect,
and also because menopausal symptoms often decline
on their own over time.
So if you saw a study like this,
where they gave women a soy protein powder
and saw a nice drop in hot flashes
over the next 12 weeks,
you'd think it looks pretty effective,
but that's the placebo powder group.
Here's the group that got the soy,
significantly better than placebo.
But it's important to recognize
how powerful the placebo effect can be.
Over the past 20 years,
more than 50 clinical trials
have evaluated the effects of
soy foods and supplements
on the alleviation of hot flashes.
Compiling the best ones together,
the placebo groups got about a 20% drop
in hot flash severity,
the soy groups achieved about a 45% drop.
So on average, the soy did about 25% better than control.
There have been two studies that compared soy phytoestrogens
head to head against hormones.
And in one study, they actually seemed pretty comparable,
in terms of reducing hot flashes,
muscle and joint pain, and vaginal dryness,
compared to placebo,
though in the other, soy did better than placebo,
but estrogen and progesterone therapy did better than both.
But the soy has the benefit
of not increasing cancer, heart disease, and stroke risk.